1. Field of the Invention
The present invention relates generally to irrigation controllers and more specifically to a computer-based irrigation system controller apparatus for controlling the timing and sequence for applying irrigation watering in a system of the type having a plurality of watering stations connected in parallel to a common source of water. The controller of the present invention is especially designed to be used with moisture sensors and permits numerous applications of relatively small amounts of water during an irrigation cycle thereby resulting in less loss due to runoff and reduced leaching and puddling caused by oversaturation.
2. Prior Art
Controllers for irrigation systems are not new. Their principal purpose is to obviate the requirement for manual control of watering systems such as sprinkler heads so that watering can be accomplished on a regular basis at times most suitable for minimally stressing the plants being watered and without requiring the presence of personnel to oversee the irrigation process. However, such prior art irrigation controller systems or timer-based systems water periodically irrespective of the need for watering and are not responsive to the moisture condition of the soil. Subsequent irrigation controllers were provided with soil moisture sensors to make the controllers responsive to the actual conditions of the soil. Such sensors indicate which watering station should be turned on or off and in which order to optimize the apparent efficiency of the irrigation system.
Unfortunately, systems that rely entirely on either timers or sensors are only as reliable as the timers and/or sensors to which they are connected. Consequently, if a timer or a sensor malfunctions, it is not unusual for a controller to permit either underwatering or overwatering which can destroy the plants by allowing them to be burned by the sun or by flooding them. Both of these conditions can, of course, be extremely costly. Furthermore, if a sprinkler head or other such water outlet becomes stuck in an open condition, then irrespective of the reliability of timers or sensors, the system will overwater and flood, thereby damaging plants and result in large costs for replacement of plants and for water waste.
There has therefore been a long felt need for an irrigation control system which reliably irrigates while conserving water and which effectively obviates any possibility for overwatering or underwatering irrespective of malfunctions in the system. There has also been a long felt need for an irrigation control apparatus which permits the monitoring of system watering statistics to permit personnel to keep track of irrigation performance during proper operation of the irrigation system as well as to assess system performance when malfunctions occur so that such malfunctions can be readily identified and corrected. There has furthermore been a long felt need for an irrigation control system where irrigation is provided by a large plurality of watering stations such as for use on golf courses, nurseries and the like and wherein such large numbers of watering stations can be controlled from a single control point providing a comprehensive display indicating the real time status for all such watering stations simultaneously. Furthermore, there has been a long felt need for a comprehensive irrigation control system wherein the irrigation parameters, such as the time that each watering station is turned on, the time between waterings at each station and the accumulated total watering time of each station, may be readily altered with a minimum of inconvenience to the user. A system controller that meets all of these needs would provide increased efficiency along with reliability and a significant degree of water conservation.